1. Field of the Invention
This invention relates in general to sensors for indicating the open and closed position of an object, and in particular to a sensor using fiber optics.
2. Description of the Prior Art
In subsea and surface well systems, a need exists for determining the position of a moving object. For example, in a valve or a choke, a closure member, such as a gate, moves between open and closed positions. In some cases, the indication must be transmitted from the subsea well to readout equipment at the surface.
Prior art devices using proximity sensors will detect the fully closed position and the fully open position. The proximity sensor may be a Hall Effect sensor or a limit switch. These sensors need a supply of electrical power. This requires wiring and connectors, which can be troublesome particularly in a subsea environment. Also, they don't indicate whether the moving object is in an intermediate position between the open and closed position. Knowing the precise intermediate position would be advantageous in some instances, particularly with chokes, which are a type of valve for controlling flow rate.